Resistivity (ρ): The property of a conductor that opposes the flow of electric current through them and independent of the shape and size of the materials but depends on the nature and temperature of the materials is called resistivity.
The unit for resistivity is the ohm-meter (Ω-m).
The resistivity of a material depends on its nature and the temperature of the conductor.
The resistivity of a material doesn't depend on its shape and size (length and area).
Materials that conduct electrical current easily are called conductors and have a low resistivity.
Materials that do not conduct electricity easily are called insulators and these materials have a high resistivity.
Resistivity is inversely proportional to the number of free electrons per unit volume of the conductor and to the average relaxation time of the free electrons in the conductor.
Resistance: The property of any conductor that opposes the flow of electric current through it and depends on the shape and size of the materials, temperature, and nature of the materials is called resistance.
It is denoted by R and the SI unit is the ohm (Ω).
The resistance is given by:
R = ρL/A
where ρ is resistivity, L is the length and A is the area of the cross-section.
EXPLANATION:
From the above discussion, we can say that
The resistivity doesn't depend on the dimensions (length, diameter, and area) of the conductor.
The resistivity depends on the material of the conductor. So option 4 is correct.
The resistivity depends on the temperature of the conductor. But the effect of temperature is negligible.
The resistivity does not depend on the density of the conductor.
EXTRA POINTS:
Difference between resistivity and resistance:
Sl.No.
RESISTANCE
RESISTIVITY
1
The property of any conductor that opposes the flow of electric current through it and depends on the shape and size (length and area) of the materials, temperature, and nature of the materials is called resistance.
The property of a conductor that opposes the flow of electric current through them and independent of the shape and size (length and area) of the materials but depends on the nature and temperature of the materials is called resistivity.
2
It is denoted by R.
It is denoted by ρ.
3
The SI unit is the ohm(Ω).
The SI unit is ohm-meter (Ω-m).
4
It is not a constant term for a given material. It can be changed by changing the length or cross-sectional area of that material.
It is a constant term for a given material. It doesn't change by changing the length and cross-sectional area of the material.